Synchronize two digital pulse trains on 6602

[itayshom]

Hello,

I'm using NI-6602 to output two interleaving digital pulse trains. Each pulse is 200ns wide, and when one channel is low the other should be high.

I also want each pulse train to be available at two output connections, i.e., I export the signal from each pulse train to another connector.

The problem is that there's significant overlap with the pulse trains. A picture is attached where you can see four waveforms of the four pulse trains.

There is no ringing or anything, just timing delays. Everything comes from the onboard 80 MHz clock. What can I do to alleviate this?

My connector block is BNC-2121.

I'm attaching the vi source. Counters 0,1 and counters 2,3 produce the two pulse trains, respectively. at PFI 36 and PFI 28. (PFI 28 is connected to User 3 BNC).

The trains are exported to PFI 33 and 32, respectively.

The pulse trains are triggered through PFI 38.

Channels 1,2 on the scope are the original pulse trains. Channels 3,4 are their duals. Also the coalescence between Ch1 and Ch3 is not perfect as in Ch2 and Ch4.

Any help is appreciated.

Itay.

[Andy-C]

Hello Itay,

It sounds like rerouting the pulse train to the PFI lines is causing a delay--there will be some (usually very small) amount of time required for the signal to move across the card itself. Can you verify which pins of the 6602 correspond to which channels on your scope image?

Best,

Andy C.

Applications Engineer

National Instruments 

[itayshom]

Hello Andy,

Thanks for the reply. I have managed to solve the problem. I just changed the PFIs I use. I used PFIs that relate to the corresponding counters, e.g. Ctr0 gate etc.

Itay.

[Andy-C]

I'm glad you were able to figure the problem out. Thanks for the update!

Best,

Andrew Church

Applications Engineer

National Instruments

http://www.ni.com/support